Method and apparatus for reducing torque changes in rock shafts

ABSTRACT

A pneumatic cylinder connected between an eccentric on a rock shaft and a structural support, for absorbing energy during one quarter of the cycle of the rock shaft during which it is decelerated, and for putting the absorbed energy back into the rock shaft during the next quarter cycle when it is accelerated. The pneumatic cylinder is preferably a double acting one with a center port to accomplish the energy absorption and redelivery to the rock shaft, at both ends of the shaft rocking movement. The rate of energy absorption and subsequent reapplication may be controlled by supplying superatmospheric pressure to the center port, and/or by starting the compressive cycle prior to the mid point of the oscillating cycle. The later is accomplished by using a piston--side port valving arrangement wherein the piston has a length that is a sizable proportion of its stroke. The cylinder may be cooled by utilizing a center exhaust port opposite the inlet port, and causing a continual flow through the low pressure end of the cylinder after the piston has proceeded past the inlet port. Bleeds may be provided at opposite ends of the cylinder to reduce the reapplication force of the cylinder, and adjustable chamber means may also be provided on one or both ends of the cylinder for adjusting the absorption rate.

United States Patent Pitt [54] METHOD AND APPARATUS FOR REDUCING TORQUE CHANGES IN ROCK SHAFTS [72] Inventor: Richard E. Pitt, Mewark, Ohio v [73] Assignee: Owens-Corning Fiberglas Corpora- 1 tion [22] Filed: March 18, 1971 [2]] Appl. No.: 125,658

Related U.S. Application Data [62] Division of Ser. No. 821,259, May 2, 1969.

[52] U.S. Cl ..267/l82 [51 l Int. Cl. ..F16i 15/02 [58] Field of Search....267/l 14, 182; 185/41; 60/7 R, 60/52 HF;9l/47l [56] References Cited UNITED STATES PATENTS 3,266,233 8/1966 Fanan Q. Q. ..60/7 R 3,155,381 11/1964 Sparling ..267/1l4 507,033 10/1893 De Normanville ..l85/4l FOREIGN PATENTS OR APPLICATIONS 729,941 5/1955 Great Britain ..60/52 [451 I Dec. 5, 1972 Primary Examiner-James B. Marbert Attorney-Staelin & Overrnan [57] ABSTRACT A pneumatic cylinder connected between an eccentric on a rock shaft and a structural support, for absorbing energy during one quarter of the cycle of the rock shaft during which it is decelerated, and for putting the absorbed energy back into the rock shaft during the next quarter cycle when it is accelerated. The pneumatic cylinder is preferably a double acting one with a center port to accomplish the energy absorp tion and redelivery to the rock shaft, at both ends of the shaft rocking movement. The rate of energy absorption and subsequent reapplication may be controlled by supplying superatmospheric pressure to the center port, and/or by starting the compressive cycle prior to the mid point of the oscillating cycle. The later is accomplished by using a piston-side port valving arrangement wherein the piston has a length that is a sizable proportion of its stroke. The cylinder may be cooled by utilizing a center exhaust port opposite the inlet port, and causing a continual flow through the low pressure end of the cylinder after the piston has proceeded past the inlet port. Bleeds may be provided at opposite ends of the cylinder to reduce the reapplication force of the cylinder, and adjustable chamber means may also be provided on one or both ends of the cylinder for adjusting the absorption rate.

11 Claims, 4 Drawing Figures METHOD AND APPARATUS FOR REDUCING TORQUE CHANGES IN ROCK SHAFTS CROSS REFERENCE TO RELATED APPLICATIONS The present application is a division of my copending application Ser. No. 82 I ,259 filed May 2, 1969.

I BACKGROUND OF THE INVENTION Mats of randomly oriented glass fibers bonded together at their cross over points are commercially produced by attenuating molten streams of glass with high velocity gases, and collecting the fibers on a continuously, moving product conveyor. The high velocity gases containing the fibers are called veils which have a diameter that is considerably less than the width of the product conveyor, and these veils are oscillated across the width of the conveyor by deflection tubes or devices that are in turn oscillated by a rock shaft. A plurality of veil producing devices, usually between six and 12, are positioned lengthwise of the product conveyor. 'The rock shaft extends longitudinally of these devices, and has longitudinally spaced crank arms connected to the deflection devices by connecting rods. The rock shaft in turn is driven by a on necting rod and crank arm mounted on the output of a gear reduction unit; and in the most refined units, the gear reduction units have camming means included therein to provide nonuniform rotation of the output crank of the gear reduction unit for the purpose of modifying the oscillation of the rock shaft from one giving standard harmonic motion to one giving uniform distribution of the fibers across the width of the product conveyor. The veil deflection means is decelerated by the rock shaft at the end of each stroke and is accelerated during the beginning of the next stroke. This occurs at opposite ends of each stroke, so that there is two accelerations and two decelerations for each cycle of the rock shaft. The acceleration and deceleration of the deflection means by the rock shaft, produces stress reversals in the rock shaft of considerable magnitude, and this situation is aggravated by the extreme length of the rock shaft and large number of power take offs that are spaced longitudinally of the rock shaft. The stress reversals are transmitted back to the driving gear reduction units, where the stack up of tolerances between gear teeth and in bearings still further magnify the stress reversal problem; and where the gear box also incorporates camming devices, a further stack up of tolerances occurs to further increase the magnitude of the stress reversal problem.

Accordingly, an object of the present invention is the provision of new and improved means for offsetting the stress reversal that is produced in a rock shaft that is used to drive reciprocating structure having considerable inertia.

A further object of the invention is the provision of means for reducing the torsion in long sock shafts having a plurality of power take offs.

A still further object of the invention is the provision of a new and improved pneumatic cylinder having a resultant pressure versus stroke curve tailored to achieve the above mentioned objects. 7

Further objects and advantages of the invention will become apparent to those skilled in the art to which it relates from the following description of the invention.

SUMMARY OF THE INVENTION According to the invention, the stress build up in a rock shaft is reduced by attaching a device to the rock shaft which absorbs the kinetic energy of the driven device during its deceleration portion of a stroke, and delivers it back to the rock shaft during the acceleration portion of its stroke According to further principals of the invention, this is accomplished by a pneuma'tic cylinder connected between the rock shaft and a stationary object, which cylinder is arranged so that its piston builds up pressure in the cylinder as it approaches one end of its stroke, and which pressure exerts a return force during the next half stroke. In the preferred construction, a double acting cylinder is pro vided with a center port which is valved off by the piston as it moves thereby, and a supply of superatmospheric gas is supplied to the center port, to steepen the energy absorption curve, and correspondingly change its energy reapplication curve. In instances where the amount of energy absorbed by the cylinder is large and high temperatures are produced, a cooling of the cylinder may be had by providing a center outlet port opposite the inlet port, and causing some of the superatmospheric gases to sweep the ends of the cylinder after the piston has moved past the inlet port..The rate of pressure build up may be further increased by increasing the width of the piston relative to the length of its stroke. In some instances, a reduction in pressure build up may be achieved by varying the clearance volume, as for example by an adjustable chamber connected to one or both ends of the cylinder. In addition, pressure bleeds may be provided so that less energy is reapplied to the driven structure than is absorbed.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of the fiber deflection apparatus and drive mechanism therefor,'that is used to make glass fiber mat insulation materials;

FIG. 2 is a schematic sectional view through one veil producing and distributing station, and is taken approximately on the line 22 of FIG. 1;

FIG. 3 is a side elevational viewof a pneumatic cylinder used to absorb energy from, and redistribute energy to, the rock shaft shown in FIGS. 1 and 2, and which is taken approximately on the line 3-3 of FIG. 1; and

FIG. 4 is a typical stroke pressure curve of the device shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS While the invention may be otherwise embodied, it is herein shown and described as embodied in the drive mechanism for the fiber distribution system of glass fiber mat producing apparatus.

Referring to FIG. 1, there is shown therein, twelve longitudinally spaced loads, or driven devices 10 which in the present instance are glass fiiber distributors, and which will later be described in detail. The loads 10 are arranged in line, and each is oscillated laterally by means of an eccentric l2, connecting rod 14, and crank arm 16 that is fixed to a longitudinally extending rock shaft 18. The rock shaft 18 is suitably journaled and supported from stationary structure, not shown. The rock shaft 18 is in turn oscillated by an adjustable crank arm 20. The crank arm 20 has a sleeve 22 thereon which can be adjustably positioned lengthwise of the crank arm 20, and which carries a pivotal connection for one end of a connecting rod 24. The connecting rod 24 is reciprocated by means of a short crank arm 26 on the output shaft of a gear reducer 28, which is in turn driven by another gear reducer 30, that in turn is driven by a constant speed electric motor 32. The gear reducers 28 and 30 are of a special design that incorporate camming means which provide rotational acceleration and deceleration at fixed frequencies to the output rotation for the purpose of changing the oscillatory movement of the driven structures from the usual harmonic motion to give .uniform fiber distribution across the fiber collection surface. For furtherdetails of the construction of the gear reducing units 28 and 30, reference may be had to the Langlois and Pitt application, Ser. No. 694,325 having a filing date of Dec. 26, I967 and assigned to the assignee of the present invention.

The load structure 10 is part of the glass fiber mat producing apparatus shown in FIG. 2 of the drawings. The fiber forming apparatus comprises a forehearth 34 having an opening 36 in a bushing plate 38 through which a small stream of glass flows continually. The molten stream of glass falls into a centrifuge basket 40 having a plurality of small openings in its periphery, and from which fine streams of glass issue in what are called primary fibers. The primary fibers are attenuated by a high velocity products of combustion which discharge from the burner 42 over the periphery of the centrifuge basket 40. Thereafter the fibers are further accelerated by the steam blower 44, which draws secondary air over the top of the blower 44 and this secondary burner 46 as is necessary to control the attenuation of the fibers. The veil of gases and fibers so produced are collected on a conveyor 48 in the form of a mat, and prior thereto are wetted out by a binder solution by means of the nozzles 50. Laterally adjustable sidewalls 52 are provided on opposite'sides of the conveyor 48 to adjust the. width of the mat produced from betweenapproximately 6 feet and 8 feet, while the veil of fibers which issues fromthe fiber forming apparatus is approximately 14 inches in diameter. In order that the fibers will be distributed uniformly across the conveyor, they are caused to be deflected from side to side of the conveyor by the fiber distributors or load devices 10.

The fiber deflection or load devices 10 are quite heavy and have a considerable amount of inertia. The load devices 10 are pivoted about a longitudinally extending axis 54 about which they must be oscillated. As is true of straight harmonic motion, the load devices 10 must be accelerated at the start of each sweep across the conveyor, and must be decelerated during the second or last half of a sweep across the conveyor, so that it can be reaccelerated back and again decelerated into the starting position. This acceleration and deceleration is, of course, accomplished through the rock shaft 18, which accomplishes the acceleration and deceleration by means of a reversal of stress in the shaft. Because of the rock shafts great length, these reversal of stresses may be in tune with the natural torsional frequency of the shaft, and which, if this occurs, produces deflections and movements which interfere with the uniform deposition of the fibers on the collection conveyor. In addition, the reversal of stresses in the rock shaft 18 are transmitted back to the gear reducers 28 and 30, where the stackup of tolerances between gear teeth, bearings, etc., produces a pounding" action. This pounding action may be further increased when the gear reducers include camming arrangements.

According to the invention, means 60 are provided for absorbing energy from one or more loads 10 during the deceleration portions of each stroke, and for reapplying at least a portion of the absorbed energy, back into the system during the portions of each stroke during which the loads 10 must be accelerated. Each energy redistribution means 60 comprises a double acting cylinder having a barrel 62 with a piston 64 therein whose piston rod 66 extends externally of both ends of the cylinder barrel 62. One end of the piston rod 66 is pivotally connected to a crank arm 68 secured to the rock shaft 18, while the cylinder barrel 62 is pivotally connected to the fixed structure 70 which supports the entire fiber forming apparatus. The cylinder barrel 62 is provided with a center pressure inlet connection 72 located at the mid point of the cylinder, and which is supplied with high pressure air through a filter 74, pressure regulator 76, and oiler 78. The cylinder 62 is also provided with a centrally located outlet 80, that is connected with a bleeder valve 82, which in some instances may be a back pressure valve set at a pressure slightly lower than the regulator 76. In some instances, each end of the cylinder barrel may be provided with a bleeder valve 84 designed to reduce the energy which is put back into the system from that which is absorbed out of the system, by relieving some of the pressure produced by the piston 64. Also in some instances, each end of the cylinder may be provided with an auxiliary reservoir 86, whose volume can be adjusted to vary the slope of the pressure-stroke curve as will later be explained.

The operation of the energy redistribution means 60 will now be explained with reference to FIG. 4 of the drawings. In those instances where a wide mat is to be made, the sleeve 22 is adjusted to a position close to the rock shaft 18, so that the rock shaft will be oscillated through as, much as 60 degrees, and so that the piston 64 of the energy redistribution means 60 will be moved through approximately a 7 inch stroke. When this occurs, the pressure regulator 76 will be adjusted to provide atmospheric pressure, or 15 psi absolute, and so that the resultant pressure-stroke curve which is provided by the device will be that indicated by the numeral 88. When a narrow mat is to be made, the sleeve 22 will be moved outwardly on the crank arm 20 as much as 10 inches to provide an angle of oscillation for the rock shaft 18 of 23. The 23 oscillation of the rock shaft 18 produces a piston movement of 4 inches, and with this piston movement, it can be seen that the same ultimate pressure as occurs with the resultant pressurestroke curve 88, can be achieved by supplying 74.5 psi absolute pressure to the inlet port 72, as by the regulator 76. This arrangement produces the resultant pressure-stroke curve shown in FIG. 4. The curve 88 is produced by subtracting the pressure on the left side of the piston, as given by the curve 92, from the pressure on the right side of the piston, as given by the curve 94;

and the curve 90 is obtained by subtracting the values of the pressure on the left side of the piston, as given by the curve 96, from the pressure on the right side of the piston, as given by the curve 98. The knee of each of the curves 92, 94, 96, and 98 are offset one inch from the center stroke position, by reason of the fact that the piston has such a width that it valves off the inlet port 72 one inch before the center of the piston reaches the zero position. .By means of this valving arrangement, wherein the piston is caused to have a valving width that is an appreciable percentage of the stroke, the rate of pressure build-up on either side of the center position, is increased, so that the center portion of the resultant pressure-stroke curve more nearly approaches a straight line. By causing the bleeder valve 82 to vent air from the cylinder, a flow of cooling air is provided through opposite ends of the cylinder during the portion of the stoke where it is not absorbing energy, and this cooling flow may be necessary in some instances to protect the seals in the cylinder, and further to provide a continual flow of lubricant through the system.

Increasing of the volume of the chambers 86, reduces the slope of the resultant pressure-stroke curves, and at the same time reduces the amount of energy absorbed by the means, and this may be necessary to accommodate a change in load condition, as for example, when one of the loads is removed from the system. Opening of the bleeders valves 84 causes the means 60 to vent some of the energy which is absorbed during a deceleration portion of a stroke, and prevent its reapplication to the system during the accelerating portion of the next stroke. This has the advantage, particularly when used at the location closest to the gear reducing structures 28 and 30, of changing the load on the gear reducing units 28 and 30, to prevent torque reversal to therein prevent the pounding action which these units would otherwise be subjected to. It will further be seen that an advantage is had in providing a number of small energy redistribution means 60 spaced longitudinally of the rock shaft 18, as opposed to the utilization of a single large means, capable of absorbing the same total amount of energy.

While the invention has been described in considerable detail, I do not wish to be limited to the particular embodiments shown and described, and it is my intention to cover hereby all novel adaptations, modifications, and arrangements thereof which come within the practive of those skilled in the art to which the invention relates.

ICLAIM:

1. The method of reducing torque fluctuations in cyclically rotation reversing shaft means which decelerates a driven device after passing a center position to the reversing point and thereafter accelerates the driven device in the reverse direction to the center point, said method comprising: absorbing energy from said shaft during the deceleration portion of the cycle by a force which increases exponentially, and delivering at least some of the absorbed energy to the shaft during the accelerating portion of the cycle with a force which decreases exponentially.

2. The method of claim 1 including: opposing said exponentially decreasing force with a positive substantially constant force during the accelerating portion of the cycle.

3. The method of claim 2 including: opposing said exponentially increasing force with a positive substantially constant force during the decelerating portion of the cycle. 7 1

4. The method of claim 2 wherein saidabsorbing and delivering of energy to said shaft is accomplished by a movable wall dividing opposing pressure chambers, and including the step of: flowing cooling air through an expanding one of said opposing pressure chambers after the movable wall moves past a generally centered position. I

5. The method of claim 1 wherein said absorbing and delivering of energy to said shaft is accomplished by a movable wall dividing opposing gas filled pressure chambers said movable wall being operatively connected to said shaft at a location remote from said shaft oscillating drive means such that said drive means reciprocates said movable wallby force transmitted through said shaft, and whereby said movable wall helps to decelerate a remote portion of said shaft before reaching its reversing point and helps accelerate said remote portion of said shaft after passing its reversing point.

6. The method of reducing torque fluctuations in cyclically rotation reversing shaft means which decelerates a driven device after passing a center position to the reversing point and thereafter accelerates a driven device in the reverse direction to the center point, said method comprising: absorbing energy from said shaft during the deceleration portion of the cycle, and delivering the absorbed energy-to the shaft during the accelerating portion of the cycle, following the reversing point.

7. The method of reducing stress in a power transmission system of the type having a shaft mounted for rotation, drive means connected to said shaft for cyclically driving said shaft in alternately reversing directions during which it decelerates said shaft until a reversing point is reached and then accelerates the shaft in the opposite direction, and an inertia device driven by said shaft, said inertia device applying a force to said shaft which opposes said drive means, said method comprising: absorbing and storing energy from the shaft during its deceleration. until the reversing point is reached, and reapplying the stored energy to the shaft following the reversing point.

8. The method of claim 7 wherein the energy is absorbed from a point on the shaft intermediate the drive means and driven device.

9. The method of claim 7 wherein the force during the absorbing step increases exponentially as the shaft approaches the reversing point and the force during the reapplying step decreases exponentially.

10. The method of claim 7 wherein said absorbing and reapplying energy to said shaft is accomplished by a movable wall dividing opposing gas-filled pressure chambers and which movable wall is remotely connected to said shaft from said drive means, and whereby said movable wall helps to decelerate a remote portion of said shaft before reaching its reversing point and helps to accelerate said remote portion of said shaft after passing its reversing point.

11. The method of claim 10 wherein said gas-filled pressure chambers are formed by a cylinder the sidewalls of which are sealingly engaged by said movable wall and in which said movable wall is moved to opposite sides of a central region, the method further including the supplying of a super atmospheric pressure to a port in the sidewalls of said central region past which the movable wall is reciprocated. 

1. The method of reducing torque fluctuations in cyclically rotation reversing shaft means which decelerates a driven device after passing a center position to the reversing point and thereafter accelerates the driven device in the reverse direction to the center point, said method comprising: absorbing energy from said shaft during the deceleration portion of the cycle by a force which increases exponentially, and delivering at least some of the absorbed energy to the shaft during the accelerating portion of the cycle with a force which decreases exponentially.
 2. The method of claim 1 including: opposing said exponentially decreasing force with a positive substantially constant force during the accelerating portion of the cycle.
 3. The method of claim 2 including: opposing said exponentially increasing force with a positive substantially constant force during the decelerating portion of the cycle.
 4. The method of claim 2 wherein said absorbing and delivering of energy to said shaft is accomplished by a movable wall dividing opposing pressure chambers, and including the step of: flowing cooling air through an expanding one of said opposing pressure chambers after the movable wall moves past a generally centered position.
 5. The method of claim 1 wherein said absorbing and delivering of energy to said shaft is accomplished by a movable wall dividing opposing gas filled pressure chambers said movable wall being operatively connected to said shaft at a location remote from said shaft oscillating drive means such that said drive means reciprocates said movable wall by force transmitted through said shaft, and whereby said movable wall helps to decelerate a remote portion of said shaft before reaching its reversing point and helps accelerate said remote portion of said shaft after passing its reversing point.
 6. The method of reducing torque fluctuations in cyclically rotation reversing shaft means which decelerates a driven device after passing a center position to the reversing point and thereafter accelerates a driven device in the reverse direction to the center point, said method comprising: absorbing enErgy from said shaft during the deceleration portion of the cycle, and delivering the absorbed energy to the shaft during the accelerating portion of the cycle, following the reversing point.
 7. The method of reducing stress in a power transmission system of the type having a shaft mounted for rotation, drive means connected to said shaft for cyclically driving said shaft in alternately reversing directions during which it decelerates said shaft until a reversing point is reached and then accelerates the shaft in the opposite direction, and an inertia device driven by said shaft, said inertia device applying a force to said shaft which opposes said drive means, said method comprising: absorbing and storing energy from the shaft during its deceleration until the reversing point is reached, and reapplying the stored energy to the shaft following the reversing point.
 8. The method of claim 7 wherein the energy is absorbed from a point on the shaft intermediate the drive means and driven device.
 9. The method of claim 7 wherein the force during the absorbing step increases exponentially as the shaft approaches the reversing point and the force during the reapplying step decreases exponentially.
 10. The method of claim 7 wherein said absorbing and reapplying energy to said shaft is accomplished by a movable wall dividing opposing gas-filled pressure chambers and which movable wall is remotely connected to said shaft from said drive means, and whereby said movable wall helps to decelerate a remote portion of said shaft before reaching its reversing point and helps to accelerate said remote portion of said shaft after passing its reversing point.
 11. The method of claim 10 wherein said gas-filled pressure chambers are formed by a cylinder the sidewalls of which are sealingly engaged by said movable wall and in which said movable wall is moved to opposite sides of a central region, the method further including the supplying of a super atmospheric pressure to a port in the sidewalls of said central region past which the movable wall is reciprocated. 